This invention addresses heat transfer predominantly for the purpose of vaporizing a constituent of a working fluid. Historically, heat transfer is done through heat exchangers comprised of substrate materials to resist corrosion, scaling, or fouling due to the working fluid by “adverse additives” within the working fluid such as salts, acids, or bases. This traditional method utilizes traditional heat exchangers to promote such heat transfer. In the past, the utilization of an immiscible fluid void of adverse additives plus the working fluid was not taken into consideration for heat transfer as a method of eliminating (or reducing) the exposure of a heat exchanger to the additives in which long-term performance would be severely challenged.
One such prior art is US 2011/0056655, being a dual-fluid heat exchanger, with the purpose of removing heat from a surface that contacts only a first fluid. The first and second fluids are immiscible, but are utilized solely for the purpose of increasing effective heat capacity and efficiency.
Another prior art is U.S. Pat. No. 4,512,332, being a solar pond where two immiscible fluids are used such that the objective is for the lower density fluid to contain the higher density fluid and ultimately to increase the overall solar conversion efficiency. The two fluids are selected with system design to minimize the interaction of the two fluids within the active area of heat transfer.
Yet another prior art is U.S. Pat. No. 4,063,419 that is another solar pond configuration. The use of a film or membrane is solely for the purpose of inhibiting one of the immiscible fluids from evaporation within the solar pond. The separation of the two immiscible fluids requires the use of a settler. A more fundamental difference is that evaporation of one of the fluids, by flash drum evaporation, takes place after the two immiscible fluids are phase separated.
Another prior art is U.S. Pat. No. 4,370,860, being a device to use brine for generating power. An immiscible fluid is vaporized through the brine (i.e., a corrosive fluid), and separation takes place by evaporation and “lifting”. The operating fluid, which is the vaporized fluid, has a latent heat flux much larger than the latent heat flux of the working fluid.
Another prior art, U.S. Pat. No. 6,119,458, is another heat exchanger method that utilizes two immiscible fluids to enhance heat transfer, but dependent on a free floating media bed to achieve “intimate” mixing. '458 is void of any surfactants by design as it requires separation of the two immiscible fluids subsequent to the heat transfer within the active area. '458 does not speak to any subsequent method of separating the two immiscible fluids, thus is further absent of any hydrophobic, super-hydrophobic, and/or superomniphobic membranes. Reference to prior art addresses the requirement of demisting equipment as a method of reducing fluid carryover when a first immiscible fluid vaporizes and thus separates from a second fluid. The two fluids are specifically selected to have differing densities for relative motion to each other.
Another prior art is U.S. Pat. No. 4,167,099, being another countercurrent heat exchange system. This use of two immiscible fluids has one fluid vaporize and thus separate from the other fluid all within a settler where the hot fluid rises. In this instance, the two fluids are intimately mixed and passed into a settler wherein the brine settles to the bottom of the settler and the hot working fluid rises to the top.
In none of the prior art methods is there any mention of specific heat capacity—relative ratios between the two fluids such that a first immiscible fluid has a temperature greater than a second immiscible fluid. The heat transfer between the two fluids with their corresponding specific heat capacity is such that the second immiscible fluid vaporizes as a result of heat transfer between the two fluids.
In none of the prior art methods is there any mention of heat of salt dissolution. Most salt solutions, notably seawater, have an endothermic heat of dissolution. The ability to recover thermal energy sufficient to provide the heat of salt dissolution requires thermal recovery from the vapor-side of the membrane to a non-phase change fluid and preferably into a second fluid such that reasonably close matching thermal flows are required between the two immiscible fluids.
None of the prior art methods have a higher membrane back-pressure above 0.5 atmospheres, where such a greater mass flow would be achieved on the vapor-side (as compared to the much lower density of a partial vacuum) of the membrane, which would require the inclusion of a superhydrophobic membrane.